Donald Trump right now minutes away from a rally in Iowa. He will be at the John Wayne Birthplace Museum in Winterset. How could you tell? It's just outside of Des Moines.

BOLDUAN: John Wayne is talking right now.

BERMAN: John Wayne, behind the mic right there. John Wayne, yes, is big. But does Donald Trump have someone even bigger waiting in the wings? Trump is touting a major announcement. He promises that a very special guest will be at one of today's events.

BOLDUAN: You will hear directly from Mr. Trump as soon as he begins speaking, once John Wayne wraps up, because he's really long winded. Donald Trump is fighting for Iowa's important voting block of evangelical Christians and social conservatives right now. Can he win their support over Ted Cruz who they are running neck and neck in that state at the moment.

Let's bring in CNN politics reporter, Sara Murray, with the latest. She's traveling with the Trump campaign, following the Trump campaign now.

Sara, what are you expecting?

SARA MURRAY, CNN POLITICAL REPORTER: Well, you know, sometimes the campaign trail takes you to places you wouldn't expect. And we're here at the John Wayne Birthplace Museum, like you pointed out. This is where he's expected to get one endorsement in the morning from John Wayne's daughter, but he has been teasing this other announcement saying it will come later in the afternoon. There is rampant speculation about what that is. A lot of political insiders and watchers seem to think it could be Sarah Palin. That is unconfirmed but it would be interesting because we haven't seen Trump supporters in this state or any state move as a block. If you look at the people supporting him, it's not just Tea Partiers, not just social conservatives and not even just sort of Independent leaning voters. It's a mix of those folks. If she does come and join him on the trail today, it will sort of be interesting to see what their star power is like combined.

Now, Trump's schedule today is a very heavy campaign schedule for him, at least. It's three stops throughout the state as well as another one tomorrow morning. And just a sign of how much the campaign is ramped up, as we're just two weeks out from the Iowa caucuses. Like you said, Ted Cruz and Donald Trump are neck and neck and doing everything they can to edge each other out at the last minute.

BOLDUAN: Absolutely right.

Sara Murray is there for us. Sara, we'll get back to you shortly.

BERMAN: The other question is, is she the only Sara who will be in Iowa today with Donald Trump.

BOLDUAN: That's right. Sara with an "H"?

Thank you so much, Sara.

Joining us to discuss the state of the race is former presidential candidate, the current Senator from South Carolina, Lindsey Graham, who just last week endorsed Jeb Bush for president.

Senator, great to see you.

SEN. LINDSEY GRAHAM, (R), SOUTH CAROLINA: You can't do bigger than John Wayne.

BOLDUAN: That's true. But can you? But can you?

GRAHAM: No.

BOLDUAN: All the speculation. Sarah Palin may be the special guest. May be endorsing Donald Trump. Some things people might know about you, one of your best friends is Senator John McCain. Also what people might remember is Sarah Palin was John McCain's running mate. Donald Trump questioned John McCain's war hero status over the summer. What would that mean if Sarah Palin now endorsed Donald Trump?

GRAHAM: Number one, if Sarah endorses Donald Trump, it would be good for Trump. I like Sarah Palin. I traveled the country with her. I appreciate her and her family very much. John Wayne and Sarah Palin can't save Donald Trump from being crazy.

If he's the nominee of our party, we're going to get creamed. He has an 81 percent disapproval rating with Hispanics. He's alienated young women. His stand on banning all Muslims puts our war plans in jeopardy. I can't stress enough, if you don't like me or Jeb Bush, fine. Make sure we win an election we can't afford to lose. Dishonest is what Hillary Clinton is perceived as, beats crazy. Donald Trump's ideas domestically and internationally are really bizarre.

BERMAN: You have said, when you talked to Kate, you said your wing of the Republican Party, to some extent, you know, has crumbled. Sarah Palin is sort of the other wing. GRAHAM: Yeah.

BERMAN: So what would a Palin endorsement do for Donald Trump?

GRAHAM: I think it helps him in this regard. I'm not so sure it gets him a lot of new voters. Probably hurts Cruz more than it helps Trump.

(CROSSTALK)

BOLDUAN: She endorsed Cruz when he was running for Senate.

GRAHAM: I like Sarah. I'm not here to say anything bad about her. I'm here to say Jeb Bush is the most qualified to be commander-in- chief on day one in my view. 1 percent of the nation has been fighting this war. Men and women in uniform represent 1 percent of us. They deserve a commander-in-chief who knows what the hell they're doing. All I can say when it comes to Donald Trump, the Democrats will destroy this guy. We have a demographic problem with Hispanics. He has an 81 percent disapproval rating before the campaign even started. If you want to make Hillary Clinton president, vote for Donald Trump. Almost anybody else could beat her.

[11:05:29] BOLDUAN: You said when we spoke when you were getting out of the race, you said you wanted someone who was ready to be commander-in-chief on day one. Also, if you endorse someone, you were going to endorse someone who can win.

GRAHAM: Yes.

BOLDUAN: You believe Jeb Bush is ready to be commander-in-chief in day one. He remains in the single digits. Where is his path? What do you see?

GRAHAM: Don't worry about national polling, Iowa and New Hampshire and South Carolina. His opponent is expectations. Can he beat expectations in Iowa and New Hampshire? We're going to make this a referendum on commander-in-chief in South Carolina, if I have anything to say about it. We owe it to those who are fighting the war to pick wisely. Choose somebody who understands that ISIL really is a threat. It's got a coherent view of the world.

One thing I can say about Donald Trump is he doesn't understand the war. If he did, he would not suggest we should ban all Muslims. The only way we can win the war is partner with the people in the faith. Jeb nailed it at the last debate.

I'm going to ask South Carolinians to think about the soldier before you vote and pick someone who would be a good commander-in-chief and bring us together. Jeb governed a diverse state very well. I don't see Trump bringing us together. He's alienated so many groups that we have problems with. This bombastic approach to the campaign and the primary is going to kill us in the general election. And Cruz is not much better. We have a chance to win an election. If we lose this election, God help the Republican Party. BERMAN: I was struck by the fact that you worked closely in the

Senate with Marco Rubio on the immigration bill. Yet, you chose to endorse someone else. You endorsed Jeb Bush. Did you see something when you were working with him that gave you reservations?

GRAHAM: When I was 44, I wasn't ready to be president. I like Marco. He's one of the most articulate people I've ever met. I think he's got a bright future. I stuck with the bill. Immigration is hard. It's killing our party. The way we approach this issue is driving a wedge between us in the fastest growing Democrat graphic in the country, Hispanics. I think it's a good solution to a hard problem. I'm looking for somebody who will stick with it.

(CROSSTALK)

BERMAN: He didn't? Is that what you're saying?

GRAHAM: In my view, Jeb is solid. What we need as a nation is steady, solid, a good temperament. He's not afraid to take on the tough issues. I like Marco. I'm not here to bash Marco. I think Marco's a very talented person.

When it comes to commander-in-chief, I think Jeb gets the war better than anybody else. When it was time to authorize the use of force to punish Assad for crossing the red line, I was with President Obama. Marco was on the other side. I think that was a mistake because we had Assad on the ropes and those in Congress who rejected the Authorization to Use Force to punish Assad gave him a second lease on life and the rest is history.

BOLDUAN: Someone else you not really worked very much with, though, but served with in the Senate, is Ted Cruz.

GRAHAM: Yeah.

BOLDUAN: They're running neck and neck. He's running ahead in polls in Iowa. Do you support Ted Cruz over Donald Trump?

GRAHAM: Absolutely not. Ted Cruz's idea of shutting down the government to repeal Obamacare made no sense to me. You're not going to get a sitting president to repeal their signature issue because you threaten to shut down the government. If the Democrats had tried this with Bush, repeal your Bush tax credits or we'll shut down the government, we would have said they're crazy. Ted Cruz on national security has been all over the board. He's a one-term Senator and his biggest accomplishment is basically running other Republicans down. At the end of the day, I don't think he has the maturity, judgment, and quite frankly, the background to be president of the United States. He's been there for two, three, four years. I can't think of anything he's done that's been very constructive.

We need somebody to bring our country together, that can work with the other side, that understands this is a war we have to win by fighting it effectively over there so we don't fight it here. Donald Trump a month ago said, why should we care about ISIL, let Russia fight them. I hope we do care about ISIL because they're coming here. BERMAN: Quickly, Donald Trump yesterday speaking before Liberty

University flubbed a Bible verse. He said 2 Corinthians instead of Second Corinthians. Does it matter in South Carolina?

GRAHAM: When you see evangelical Christians, the last person who comes to mind is Donald Trump. All I can say is he's appealing to people's fears. We need to be appealing to their hopes. At the end of the day, if the evangelical Christian community gets behind this guy, know what you're getting. I'm a flawed person as much as anybody else. You're getting someone who is unelectable. You're handing the White House to Hillary Clinton. And if after this last debate you don't understand she's a third term of Barack Obama, you're not listening. You're making it impossible to defund Planned Parenthood. All the policies you hate are going to become reality for four more years because Mr. Trump cannot beat anybody. He's not going to be president of the United States demeaning every group in America. That's not going to happen. We're better than this.

[11:10:16] BOLDUAN: Senator Lindsay Graham --

GRAHAM: Thank you.

BOLDUAN: -- endorsing Governor Jeb Bush. Iowa, two weeks away.

Great to see you, Senator. Thanks for coming in.

GRAHAM: Thank you.

BERMAN: Thanks, Senator. Appreciate it.

Breaking news this morning. The Supreme Court says it will decide the fate of President Obama's executive actions on immigration, announcing it will take up the issue this term.

BOLDUAN: More than two dozen states are now challenging the president's actions, which shield millions of undocumented immigrants from deportation.

Let's get kind of the state of what this means now with senior legal analyst, Jeffrey Toobin, who is joining us on the phone.

Jeffrey, what does this mean? The court is going to take it up, obviously, this session, meaning they could decide by early summer. What does this mean?

JEFFREY TOOBIN, CNN SENIOR LEGAL ANALYST (voice-over): Well, it is certainly good news for the Obama administration that the court took the case. Because the status quo is that the lower court had put a hold on the whole program. So if the Supreme Court hadn't taken it up, President Obama would leave office without implementing this policy. At least he has a chance of winning by the end of June and having this policy reinstated, which could affect more than four million people, so the stakes are very, very big in this case.

BERMAN: Any sense of where the court is or where the court would be on this? You know, it may come down to standing, I suppose, whether the states even have the right to challenge the ruling. But when it comes to immigration and executive authority, has this court given any indication about where it stands?

TOOBIN: Well, you know, this is a kind of paradox situation in this court because there is a conservative majority. A roughly there are five Republican appointees and four Democratic appointees. And Republicans historically have been sympathetic to arguments of expansive executive power. However, when it comes to Barack Obama and his authority, the court has been somewhat more restrictive. Again, the question always in court is how much is it about the ancient legal principles and how much is it about contemporary politics. This is difficult case to handicap. I think the oral argument, which will be in April, will tell us a good deal, but I think this is a very difficult case for predict.

BOLDUAN: The Supreme Court taking it up in the heat of battle, in the heart of this political season. They're taking up a controversial issue at a very difficult time, that's for sure.

Jeff Toobin, Great to see you -- hear from you. Jeff, thanks.

Coming up for us, are the Democrats in store for a sequel to 2008? Why Hillary Clinton's campaign is ready for a brutal primary fight. Are they concerned at how long this could go on? We're going to speak live with Bernie Sanders' campaign manager about what than means coming up next.

BERMAN: Plus, behind bars in Iran. A man who spent years in an Iranian prison joins us live to talk about the ordeal and what it's finally like to be free.

And stunning new details about the extraordinary security measures taken to make sure el Chapo doesn't escape again, from dogs to motion sensors, maybe even the guards who can't be bought. We'll take you inside that prison.

(COMMERCIAL BREAK)

(BEGIN VIDEO CLIP)

[11:17:44] SEN. BERNIE SANDERS, (I), VERMONT & DEMOCRATIC PRESIDENTIAL CANDIDATE: From the bottom of my heart, above and beyond ideas, if you want somebody who is going to beat Donald Trump, who is going to beat the other Republicans, I think Bernie Sanders is that candidate.

(END VIDEO CLIP)

BERMAN: An endorsement from Bernie Sanders to Bernie Sanders.

BOLDUAN: To Bernie Sanders. That was Bernie Sanders moments ago telling a crowd of Iowa supporters that he, not Hillary Clinton, is the best candidate to take on Donald Trump. Sanders is coming off a massive rally in Birmingham, Alabama, yesterday, as part of his new aim to chip away at Clinton's quote, "southern firewall."

BERMAN: Now the Clinton campaign is preparing for a much longer and tougher primary battle.

Joining us now is the campaign manager for Bernie Sanders, Jeff Weaver.

BERMAN: Two endorsements in less than five minutes from unlikely sources there.

You're in Iowa. The polls have you closing in, in Iowa. At this point, is Iowa a must-win for Bernie Sanders?

WEAVER: No, it's never been a must-win, but it is a state where we have to do very well. And we are going to do very well here. We have a tremendous ground operation here in Iowa. The Senator has been here a lot, and will be here more in the final days. It's clear there's a lot of energy on the ground here in Iowa. He's crisscrossing the state. And so we're very happy with how things are going here in Iowa.

BOLDUAN: Jeff, after Iowa, after the early states, it gets a little bit more complicated. Some are going to say, when you talk about the southern firewall for Hillary Clinton. One important voting bloc that your campaign needs to look to is African-American votes in the south. In South Carolina, some of the latest polling has support of African- Americans, 82 percent for Hillary Clinton, 11 percent for Bernie Sanders. What do you do about that?

WEAVER: Well, there's also another poll out this week that had Senator Sanders at 18 percent. That's an improvement from where when we were single digits with African-Americans in South Carolina.

But let me say this. There have been other polls around the country having him doing better with African-Americans. It's always been the case that success in early states helped to build support in later states. That's the structure of the system. When we go into South Carolina, get closer to the election, when he's done well in Iowa, in New Hampshire, it will have an influence on the way all voters look at him in those subsequent states.

(CROSSTALK)

[11:20:12] BOLDUAN: So you're not concerned about even an 80 percent/18 percent?

BERMAN: 11 percent isn't that high.

(CROSSTALK)

BERMAN: It's not very high. I remember talking to you after the Democratic debate in Las Vegas. And you said, you know, you were reaching out right then. That was October. It's now January. You know, it hasn't gone up a heck of a lot since October.

WEAVER: We were at 5 percent here in Iowa at one point. So things can change quite quickly. Even a month ago, we were down 25 points here in some polls. Things can move very, very quickly in Iowa and New Hampshire. This has been the focus where the candidates now have advertising on television, have spent a lot more time. And what we have seen throughout this campaign is the more voters see and hear from Bernie Sanders, the more voters move toward him. As the campaign progresses, after Iowa and New Hampshire, as we're focusing more on Nevada and South Carolina and other states, voters there will have more opportunity to see Senator Sanders, to see us in the paid media as well. That will move voters as it has in other states.

BOLDUAN: You know who sees Bernie Sanders now? Donald Trump, this is what he says about the official running against Sanders. Listen to this, Jeff.

(BEGIN VIDEO CLIP)

DONALD TRUMP, (R), PRESIDENTIAL CANDIDATE & CEO, TRUMP ORGANIZATION: At least Bernie is getting some action. He gets much smaller crowds than me but at least he gets action. Oh, would I love to return against Bernie. I would love --

(CHEERING)

TRUMP: Oh.

(CHEERING)

TRUMP: That would be a dream come true. But actually, I must say, I have my mind set on Hillary.

WEAVER: I think, if you look at the polls, Senator Sanders crushes Donald Trump. And what is significant about what we're seeing now in head-to-head matchups between Senator Sanders and Secretary Clinton and various Republicans is we're increasingly seeing that Senator Sanders does better against these Republicans including Trump and especially Trump, than does Secretary Clinton. There were polls recently in Iowa and New Hampshire where people have had the most chance to see the candidates, all the candidates, and in every case, Senator Sanders did better than Secretary Clinton against every Republican in both states.

BERMAN: Jeff, the Senator has come out with this plan for Medicare for all, a single payer health care plan.

WEAVER: Sure. BERMAN: There's been talked about whether it's realistic that it could get through Congress or not. What percentage chance do you think that Congress will pass a single-payer health care plan in the next four years? Handicap that for me.

WEAVER: John, this is the point. The question for Democrats is this. Do you want a Democratic candidate whose vision is limited to what that candidate thinks the current Republican Congress will accept? If that's what you want, you should vote for John Kasich. If you want a Democrat who has the vision like FDR, LBJ, and Harry Truman, but who has long experience as a practical legislator, but who carries forth a vision, who will shoot for the end zone even though he knows on occasion he may have to hand off for a three-yard first down, that's Bernie Sanders.

(CROSSTALK)

BOLDUAN: Even if we give you that, even if we give you that, what percentage chance that he passes it in the next four years?

WEAVER: That's going to depend a lot on what the next Congress looks like when the next president is sworn on. On that point, let me also say, what we're seeing out there are the type of crowds that Bernie Sanders is drawing, the excitement, the enthusiasm, the young people, the nontraditional voters, the overwhelming support among Independent voters which is critical to a Democratic win. If Bernie Sanders is the nominee, he will have the kind of momentum which is going to sweep in, not just himself, but other Democrats as well. You remember when President Barack Obama was elected, 10 Democratic Senators were elected with him. That's the kind of --

(CROSSTALK)

BERMAN: And he could not get single-payer health care through --

BOLDUAN: With a Democratic Congress.

BERMAN: -- even with a Democratic Congress and 10 Democratic Senators.

(CROSSTALK)

WEAVER: Look, no one says it's going to be easy, John and Kate. But let's hold the vision out there. Let's hold on to a core Democratic values in this campaign.

BERMAN: Jeff Weaver, great to see you in Des Moines, Iowa. Please come back. Nice talking to you.

WEAVER: You've got it. Take care. Thank you very much.

BOLDUAN: Stay warm, Jeff. See you later. Thanks so much.

WEAVER: Thanks.

BERMAN: Any moment now, Donald Trump is expected to speak in that very same state.

(CROSSTALK)

BOLDUAN: John Wayne, get off the podium.

BERMAN: A filibuster from John Wayne right now.

Donald Trump says a big announcement is coming today. He says he has a very special guest who will appear with him today. I do not think he's talking about Donald Trump. There is an expectation -- Sorry, I don't think he's talking about John Wayne. There is an expectation of a big endorsement today.

[11:24:47] BOLDUAN: It was funny when you said Donald Trump, too.

Also ahead for us, as Michigan's governor says, the water crisis in his state is his Katrina. We're going to speak with a doctor who is now leading the efforts to check and treat some 27,000 children who could be impacted by lead poisoning in that city of Flint, Michigan, because of the water crisis. We'll be right back.

(COMMERCIAL BREAK)

BOLDUAN: Now that the Americans Iran held -- now that the Americans that were held in Iran are free, we're learning more about the deal making that went on to lead to their release. CNN has learned that the U.S. Attorney General Loretta Lynch had reservations about the prisoner swap setting a precedent. Sources familiar with the negotiations say she and other officials pushed for more assurances that all U.S. citizens would be freed and that Iran would turn over all information it has on the location of the retired FBI agent, Robert Levinson.

BERMAN: Joining us now is Shane Bauer, a senior reporter at "Mother Jones."

He was held in Iran for more than two years after being taken into custody by Iranian border guards. Shane was hiking with his girlfriend, now wife, and a friend on the Iran/Iraq border when they were arrested charged with spying and entering the country illegally.